Fire alarm



Sept. 12, 1961 v. E. PRATT ETAL 2,999,477

FIRE; ALARM Filed June 9, 1959 2 Sheets-Sheet 1 y JNVENTORS 4C MWA/Em?.E Pff/277 [0MM/V0 C /Q/P/lrr 2 Sheets-Sheet 2 Sept. 12, 1961 v. E.PRATT ETAL FIRE ALARM Filed June 9, 1959 2,999,477 rma ALARM Verneur E.Pratt, 2000 Skyline Drive, Fullerton, Calif., and Edmund C. Pratt,3591/2 West Road, La Habra,

Calif.

Filed June 9, 1959, Ser. No. 819,163 7 Claims. (Cl. 116-406) "Ihisinvention relates to alarms and in one of its more particular aspects tolire alarms.

Many types of alarms have been proposed and/or used in the past.Electrical alarms are the most advanced type of Valarm particularly inthe tire alarm field. Electrical alarms, however, are relativelyexpensive and have the disadvantage that they are rendered inoperativeby loss of electrical power and which power loss is usually a result ofthe very tire for which the alarm was installed to detect. As a result,alarms having selfcontained power sources, such as spring wound alarmshave been proposed to avoid both the diliiculties and the expense of theelectrical alarms.

l'Ihis invention relates to an improved and inexpensive and easy toinstall alarm which is of the self-contained power type and of a lightweight construction for use in houses, offices, industrial plants,warehouses, boats and the like. rThe alarm is substantially housedwithin the bell therefor and has its operating mechanism further encasedto allow the alarm to be used in any environment, including a corrosiveenvironment. This encasing is further arranged to permit the operatingmechanism to be free from tampering or being rendered inoperative byforeign matter such as bugs, insects, and the like accumulating therein.

The invention is best described in its embodiment as a re alarm andwhich re alarm includes a cup-shaped bell deiined to house the completemechanical operating mechanism within the bell. The heatsensitiveelement for detecting the preselected increase in ambient temperature,such as produced by a fire, is mounted on the outside of the bell in aposition to be readily visible as well as accessible. The self-containedoperating mechanism for the alarm is encased within a sub-assembly denedto completely seal ott the mechanism. The mechanism is powered by meansof a spring motor arranged to provide a continuous driving action for ahammer to sound or ring the bell.

In one specitic embodiment of the invention spring means in the form ofa constant tension spring is normally wound on a rotatable storage drumand connected to a rotatable drive drum to 'oe wound thereon whereby thestored energy thereof is utilized to continuously drive ahammer with aconstant torque for sounding the alarm. The spring is wound on the drivedrum by manually winding the spring thereon through the provision of awinding knob accessible at the back of the alarm.` The storage and drivedrums are both rotatably mounted on shafts with the shaft for the latterdrum being provided with a drive gear to be rotatably responsive to theunwinding of the spring from the drive drum and thereby through suitablegearing transmit this driving action to the hammer for sounding orringing the bell.

The hammer is rotatably mounted to be continuously responsive to thedriving action of the gearing and is constructed and arranged to therebycontinuously sound the bell at substantially the same sound level. Thehammer includes an arm having heads very loosely mounted at oppositeends thereof. The hammer is mounted on the subassernbly but outside ofthe sealed interior or chamber housing the operating mechanism properand which sub-assembly is defined to provide a hammer chamber whereinthe hammer rotates. The bell is pro- Patented Sept. 12, 1961- arrangedhammer at a high rotary speed to produce a` loud and distinctive ringingsound and which ringing4 sound is easily distinguished from the usualenvironmental noises or sounds.

he lhigh rotary driving speed of the hammer is' achieved by theprovision of step-up gearing arranged intermediate the drive gear andthe driven shaft mountingV The driving action of thistransmissivegearing is selectively controlled by a control means in-Y'the hammer.

cluding a control member engageable and disengageable with the gearingand which locks or unlocks the spring wound on the drive drum. Thiscontrol operation is.

aected, in this instance, through the provision of a stopmember or lipdened on the face of a transmitting gear 'to restrain the rotationthereof.` This control member is further arranged to extend outwardlyoiI the subassembly and through the bell proper where it cooperates witha latch which may be centrally mounted on thel outside ot the bell. Theoperation of the latch governs; whether the spring is locked orunlocked. When the alarm is to be used for detecting tires the latch maybe in the form of a heat responsive link arranged to deform at apreselected temperature and allow the control member to disengage fromthe gearing and thereby allow the spring to unwind for sounding thealarm.

The alarm also includes means for visually indicating when the alarm isnot in operating condition and the spring should be wound onto the drivedrum. This indicating means measures the length of spring wound on thestorage drum and signals the need for a rewinding operation when all ofthe spring is wound on the storage drum whereby the alarm isinoperative. This indicating means comprises a spring biased armengaging the outer wrap of the spring on the storage drum and mountingaliag which is rotatable into a visible position when the spring isstored on the storage drum and is in la nonf visible position within thebell when substantially all of the spring is stored on the drive drum.This indicating means signals the operating condition of the alarmindependently of the condition or position of the heat responsiveelement which may be readily detected by an observer.

The invention is explained in more detail in the following descriptionand in the accompanying drawings, in which: l

FIG. 1 is a side elevational View, with the bell partially broken awayand the exposed control mechanism shown in cross-section of the alarmembodying the in-` vention shown mounted in a horizontal position;

FIG. 2 is a bottom plan view of the alarm of FIG. l, with the back coverremoved, and showing a portion of the bell and the positions of thevisual indicating means and of the hammers in dotted outline;

FIG. 3 is a partial, cross-sectional view taken along the line 3 3 ofFIG. 2 with the spring removed from the drive drum, the bell broken awayand the back cover shown in position; and

FIG. 4 is a sectional view, with parts in section md' parts broken away,taken along line 4 4 of FIG. 3.

Now, referring to the drawings, the alarm 10 will be described in moredetail. The alarm 10 comprises a bell 12 housing a sub-assembly 14 forthe operating mechanism and which sub-assembly is substantially housedthe bell. 'Ihe sub-assembly 14 is dened to mount essere??? atwindingknob 16 anda visualindicating means or tiag. 18 in a manner to renderthem readily accessible when the alarm is unmounted. A hammer 17 forsounding thefbell 121 protrudes `from one side of the sub-assembly 14.Thev sub-assembly'lll and the bell 12 are intercon-v nected by meansincluding control operating means arranged on the exterior of the bell12 to allow the bell to be either manually or ztutonnaticallyV soundeddepending; on the application thereof. When the alarm is to be used asa". re' alarm, the control. operating means includes a heat sensitivelatch 20. The alarm 10 is controllably locked or unlocked to anoperating relationship by meansof the-heat sensitive element 20.

The bell 12 is of a cup-shaped construction with. a skirt of suicientlength to house the sub-assembly 14 almost completely therein. The bell12 is constructed of a material that will provide a loud sound uponbeing struck. The bell 12 includes a sounding or striking pin 122Lformed integral with the bell or irrnly fastened thereto. The provision.of the striking pin 1291 allows the bell 12 tov be sounded withoutstriking the bell proper as will become more apparent hereinafter. Acentral aperture for the b ell 12 is deiined to receive an operatingcontrol member or pin 22 cooperating with the heat sensitive elementaswill ybe more evident hereinafter.

The sub-assembly 1d is 'arranged to house the operating mechanism forthe alarm lil in a sealed chamber defined by a substantially cup-shapedmember 24 and a cover member 26. cooperating therewith. The cup-shapedmember 24 is of a smaller diameter. than the inside diameter oi thevbell. 12 to allow the sub-assembly 14 to be readily positioned therein.The cup-shaped member 24 is also provided with a central aperture toslidably receive thev operating control member. 22 when it is axiallyaligned with the bellv 12.

The sealed chamber for the operating mechanism is defined by enclosingthe cup-shaped member 24 with. the cover 26 and which cover carries aplurality of securing pins 26 disposed at spaced points around its outerperiphery. The cup-shaped member 24 is also provided. with sockets 24ato receive the pinsZoc. The ends 0f the pinsV 26 are of a, length toprotrude from the sockets 24a and may be peened over to connect thecup-shaped member 2d and cover 26. The thus arranged cover 26 closelyfits the cup-shaped member. 24 to enclose the latter for sealing theoperating mechanism proper, except for an opening through which only thehammer 1.7 protrudes. The operating mechanism, however, is sealed fromthis. hammer opening by the provision of a mounting plate 28.

n The mounting plate 28 is flush with the outer periphery of thecupehaped member 24. The mounting plate 28 is. mounted in this fashionthrough the provision. of three feet or posts similar to the oneidentilied by the reference character 24h integral with the; member 24and defined to receive and support the plate 28. The three supportingfeet formed have pins 24C at the ends to be received in the openings 28afor the mounting plate 28 and which pins secure the mounting plate tothe cup-shaped member 24 when their ends arev suitably peened. Themounting plate 28 not only seals off. tlre'operating mechanism Withinthe chamber but also cooperates with an upraised portion 26a defined onthe cover 26 to define a hammer chamber: wherein the hammer 17 rotates.

It will now be seen that any operating mechanism housed within thissealed chamber will be free of corrosives inv the ambient air and willnot allow insects to enter.

The operating mechanism enclosed within the abovedescribed sealedchamber when a spring motor for providing a constant torque is employedincludes the illustrated storage drum 39 having a rotatably mountedshaft.

The storage drum shaft 32 is rotatably mounted between' thei cup-shapedmember 24 and the mounting plate 23 through the provision of a socketdefined on the cupshaped member 2li'A to rotatably' receive the storagedrum shaft32 and which. shaft hasitsnoppos'ite endl deiinedwith.:

4l( a socket to receive a pin provided on the adjacent side of themounting plate 28 (not shown). A commercially available constant tensionspring 34 is wound on the storage drum 30 and which storage drumnormally stores the spring when the alarm 1G is rendered inoperative.The essential characteristic of the spring 34 is that it provides aconstant torque throughoutits entire lengthyto thereby provide aconstant driving action. The spring 34 is mounted onthe storage drum 3)in a manner whereby when it is unwound therefrom it will quickly returnthereto.

A drive drum 36 mounted adjacent to the storage drum Btl is connectedwithv an end 34.it of the spring 34; see FIG. 4. The drum 36 is mountedon a rotatable shaft 38 journaled in the same general fashion as thestorage drum 30. The drive drum shaft 3S is rotatably positioned in asocket on the cup-shaped member 24 (see FIG. 3) and extends therefromthrough the mounting plate 28 and the cover 26 to receive the windingknob 16'; see FIG. 3. The cover. 26 isV defined with a socket 26barranged adjacent the` raised portion. 26Bl to receive the winding knob16 which is connected to the drive drum shaft 33 by means of a screw 4i)threaded thereto. The rotation of the knob 16 will cause the spring 34to be unwound from the storage drum 3i) and onto the drive drum 36 toplace the alarm 10 in an. operating condition. A drive gear 42 ismounted on. the rotatableshaft 35 intermediate the drive drum 36 and thewinding 'knob 16 withinthe sealed chamber to be rotatable therewith. Theunwinding of the spring 34 from the'drive drum 36 willcause the shaft 38to rotate.. and thereby rotate the drive gearV 42. The drive gear 42visA arrangedin driving engagement with the splined end' of a. stubYshaft 44 rnountingan intermediate or transmitting'gear 46 rotatabletherewith. This transmitting gear 46 is dened to step up the rotaryspeed of the drive gear 42 and includes a stop member or lip 46a denedintegralA therewith on the face adjacent the bell 12.

The drive drum shaft 38 may also be arranged to mount a contr-olmechanism to lock the gearing and thereby the hammer when the spring/34is being wound onto the drive drum 36. This control mechanism may be aratchet 37 mountedto be rotatable with the drive shaft 38 cooperatingwith a detent 39 mounted on the drive drum 36 and engaging'the ratchet37. ItV will be recognized that this mechanism will prevent the drivingof the gearing and hammer while the spring 34 is being wound onto thedrive drum 36but yet' allows the drivingof the hammer when the spring 34is being unwound from the drive drum 36.

The hammer 17 is mounted to be rotated by a stub shaft 48 having asplined end arranged in driving relationship with the transmitting gear46. The hammer 17 is defined by means of a pair of spaced arms 50 and52', one of which is dened with a pairof pins adjacent thek oppositeends to be received in suita'ble apertures in the other arm, as shown inFIG. 3. The arm 50 is defined with ther pins 505 to be received in asuitable aperture of the arm S2; as shown in FIG. 3`. The pins 50a mounthammerheads 54 in a very loose relationship. This a1'.- rangement isclamped together by the provisionv of a screw threaded' into the endofthe shaft 32.

The liammerheads 54 are tubular members having a large internal diameterrelative to the diameter of the pins 50a whereby they will moveoutwardly relative to the arms 5t) and 52 under the inuence ofcentrifugal force' and inwardly in response to an inwardly directedforce.

The hammer17 is mounted over the mounting plate 28 It should be notedthat this hammer and bell arrange-- ment is useful to provide agoverning. action to control' the release of the stored energy of. thespring. The actionof the hamm'erheads 54 upon striking the` pin 12a andvtraveling; beyond the pin under the urging ofthe spring.

t is such as to govern 'or delay the release of the energy stored in thespring. Thisfc'oaction causes the energy of the spring to be released ata lower rate and the speed of the hammer 17 to be reducedrelative to abell not provided with a strikingpin. This governing action causes thebell 12 to befsoundedover -a longer period of time lfor a given lengthof spring, whether the spring be a coiled spring, constant tensionspring o'r otherwise. Accordingly, a lon'g sounding period may beprovided with a length of 'spring readily housed within the bell proper.

The operating control-means for sounding the alarm 1t! includes thecontrol 'pin l22V andi the heat sensitive latch 20. The control member!22 'isarranged Vwith a spring 62. seated in acentral s'oc'ket'fo'ri thecup-shaped member 24 and labutting a shoulder dend intermediate the endsof the pin whereby the spring constantly urges the control pin throughthe central aperture for the cup-'shaped member 24 and o'n th'c' outsideof the bell 1-2. The stop memb'er 46El is located oh the transmittinggear 46 whereby it will be rotated into engagement with the control pinZ2 when the latter is in a depressed position. This depressed or lockedposition is achieved by securing the latch 2d between the 'clips`'defined on an ornamental star 64 mounted on the outside face of thebell 12. The star 64 is secured to the Abell 1'2 by means of a pairoflscrews connected to lthe cup-shaped member 24, The latch 26 whenclipped forces 'the control pin r22 to the depressed position wherebythe transmitting gear is prevented Vfrom rotating until the control pin2'2 is positioned out of the path of the gear 46.

The relative Ilocation of the spring 34, that `is whether it is storedon the storage drum 30 or on the drive drum 36 is indicated through theprovision of the ag 1S. The Hag 18 is mounted to be rotatable with ashaft 65 carrying a sensing arm 68 adjacent its other end. The shaft 65extends through the mounting plate 28 and the cover 26. This exposed endof the shaft 65 is threaded to secure the ag 18 thereto by means of ascrew. A biasing spring 67 is wound around the portion of the shaft 65extending between the mounting plate 28 and the cover 26 to urge thespring sensing arm 68 continuously against the outer Wrap of the spring34 wound on the storage drum 30. The sensing arm 68 arranged in thisfashion also functions as a stop to prevent the winding of spring 34 insuch a manner so as to disengage it from drum 3i) and from deforming itby reverse bending. The flag 18 is in this manner positioned to bewithin the outer peripheral edge of the bell 12, when the spring 34 iscompletely wound on the drive drum 36 and is rotated outwardly beyondthe peripheral edge of the bell 12 when the sensing arm 68 is moved awayfrom the storage drum 30 as a result of the spring 34 being rewoundthereon; as shown in FIG. 2 in dotted outline. The flag 18 may be markedwith a legend such as Rewind to indicate even more readily the conditionof the alarm.

A mounting clip 70, as shown in FlG. l, is connected to the cover 26 bymeans of a pair of screws over the socket 26b defined for the windingknob 16. This mounting clip 70 allows the alarm 10 to be readily mountedand dismounted in either a horizontal or vertical position.

With the above structure in mind, the operation of the alarm will now bedescribed assuming the latch Ztl is a heat sensitive element selected todeform at an elevated temperature in a manner to allow the control pin2,2 to disengage the transmitting gear 46. The spring 34 is manuallywound onto the drive drum 36 by rotating the knob 16. The flag 18 atthis time will be rotated within the periphery of the bell 12 andtherefore not visible when the spring 34 is stored on the drum 36. Whenthe ambient temperature of the room in which the alarm 1i) is to protectreaches a preselected elevated temperature, the latch 20 will al-low thecontrol pin 22 to disengage the transmitting gear 46 and thereby allowthe spring 34 to wind back onto the storage drum 30. The unwinding ofthe spring 34 from the drive drum 36 provides the 6 rotary drivingaction of the drive gear 42. The rotation of the drive gear 42 drivesthe stub shaft 44 which in turn rotates the intermediate gear 46. Sincethe control `pin 22 is disengagedl from the transmitting gear 46 thisdriving action is coupled to thershaft 48 for driving the hammer 17. Thehammer' 17 is then rotated at a high speed whereby the hammerheads 54are driven to their outer extreme under the inuence of centrifuga-lforce and upon being rotated into engagement with the sounding pin 12astrike it a glancing blow, are then forced inwardly by the pin 12a, andin passing by the pin, once again are forced outwardly under the inuenceof centrifugal force; see FIG. 2. This glancing blow of the sounding pin12a is effective to loudly sound the bell 12. The hammer 17 continuouslysounds the bell in this fashion as the hammerheads 54 are rotated tostrike the pin 12a. This sounding action continues at high speed and atthe same loudness until the spring=34 is wound back on the storage drum30. After the spring 34 i's relocated on the storage drum 30 the sensingann 68 will have moved the flag 18 to indic`a`te a rewin'd is necessary.It should be noted that this rewind signal provided by the liag 18 is inaddition to the indication of the condition of the alarm which isrevealed by the condition of the latch or heat sensitive element 20. l

The continuous sound ofthe bell llt) in this fashion has been arrangedto provide an extremely loud sound level of a nature readilydistinguished by a normal sleeper from other environmental soundsemanated by sirens, telephones, buzzers, whistles, doorbells and thelike. The bell 10 'providesdthis continuous sound for many minutes.

What is claimed is:

1. An alarm comprising a Ibell having a sounding pin formed integraltherewith, a sealed sub-assembly substantially housed within said bellcomprising a cup-shaped member and a cover member enclosing the latter,a storage -drum rotatably mounted in said sub-assembly for storing aspring, a constant tension spring normally stored on said storage `drumand adapted to return to same when unwound therefrom, a drive drumrotatably mounted in said sub-assembly and having one end of the springconnected thereto for winding the spring onto same from said storagedrum, a hammer having movable sounding heads at opposite ends thereofand rotatabiy mounted in said sub-assembly adjacent the sounding pin toallow a sounding pin to extend outwardly therefrom for striking the pin,step-up transmission gearing mounted in said sub-assembly in a drivenrelationship with said drive drum to be responsive to the rotation ofsame provided by the unwinding of the spring from said drive drum andhaving a driving connection with the hammer for continuously drivingsame at a constant rate throughout substantially the whole length of thespring, means mounted externally of said sub-assembly and connected tothe drive drum for winding the spring thereon, and control meansextending outwardly of said sub-assembly and said bell engageable anddisengageable with the gearing to selectively control the operation ofthe gearing, and latch means mounted on the bell operable to lock andunlock the control means into and out of engagement with the gearing toselectively control the sounding of the bell.

2. An alarm as defined in claim l wherein said latch means includes aheat sensitive element visibly mounted on the bell to be completelyexposed to the ambient air and engageable with the control means toposition the latter into engagement with the gearing at normal ambienttemperatures and responsive to a preselected ambient temperature todisengage the gearing.

3. An alarm comprising a bell having a sounding pin formed integraltherewith, a constant tension spring ,a storage drum rotatably mountedfor storing said spring, a drive drum rotatably mounted and having oneend of the spring connected thereto for winding the spring onto samefrom said storage drum, means connected to the -mounted hammer having apair of striking heads loosely Ymounted thereon, said hammer beingmounted.- adjacent the sounding pin for striking the pin and therebysound- 'in'g the bell, transmission gearing mounted in a driven jrelationship to be responsive to the rotation 'of said drive drumprovided by the unwinding of the.' springther'efrom Aand having adriving connection with the vhammer for rotating same at a constantrate, said gearing including at least a single gear having a stop memberdefined thereon, and control means engageable and disengageable with thestop member for locking -and unlocking the transmission gearing toselectively control the sounding ofthe bell. g

I 4. A fire alarm comprising a bell, a rotatable drum `having a constanttension spring Wound thereon, a rotat- 'Sable drive drum connected'withone end of the spring,

'f said gearing to control the unvvinding of the spring from the drivedrum.

5. A fire alarm as defined in claim 4 including a 'separate housingforsealing said rotatable drm'srincluding the spring and the gearingfrom corrosive environments.-

6. A re alarm as deined in claim 5 including means responsivelto thelength ofi-'spring wound on ythe'storage drum for visually indicatingthe operating condition of the alarm. e

7. A re alarm inclu-ding a bell having a striking pin formed integraltherewith; a sealedsub-assembly snbst'an tially housed Within the bellcomprising a rotatable harnfmer extending therefrom for sounding thebell, and spring means connected to said hammer for continuouslyrotating same; said hammer having anl arm loosely mounting strikingmembers adjacent each end of the arm, the striking members being mountedon the arm whereby upon rotation of the hammer under urging or" thespring means the members -move relative to the arm intofthe path of thestriking vpin to strike the bell a glancing blow and are moved out ofthe path of the pin by thepin to govern the release of energystoredl inthe spring and thereby extend the length of time the bell is sounded,and heat sensitive control means Within the sealed subassemblyconnectedA to the spring means for controllably actuating the release ofenergy from said spring means.

References Cited int-he tile of this patent' 'UNITED STATESlATENTS565,306 strain Aug. 4, ,1896

815,1111 Meyers et al.l Mar. 13, 1906 1,415,207 Swanberg .V May 9, 19222,625,902 Sorensen a.. Jan. 20, 1953 2,871,815 Krieger -4.7----7 Feb. 3,1959 FOREIGN PATENTS 526,262 June 28, 1921

